The purpose of this invention is to provide a safety device that relieves the pressure from a pressurized tire before removal of key components that could cause a catastrophic failure if removed while pressure remains in the tire. A typical example of the need and purpose of the invention is presented by a tubeless tire mounted on a two-piece rim. In this situation, if the assembly nuts are removed without deflating the tire first, a catastrophic failure of the remaining fasteners may occur after some of the nuts are removed, causing injury to the personnel disassembling the tire/wheel combination. Thus, a primary application of the instant invention is avoiding disastrous and sometimes explosive decompression of inflated tires on the disassembly of a two piece wheel assembled to an inflated tire.
FIG. 1 shows a typical two piece wheel assembly without a central tire inflation valve. The two-piece wheel assembly 1 includes a tire 2 with a body portion 2A and an inner cavity 2B containing a pressurized fluid (usually air). The wheel assembly 1 includes a rim portion 1A formed coaxially on opposite ends thereof with outwardly flaring circumferential flange sections disposed to be engaged by the beads of tubeless tire 2. A transverse wall section, disc portion 1B, extends transversely of the axis of the wheel assembly 1 and its rim 1A, and includes a central opening (hub bore area 1C) disposed coaxially on said axis. The wall section of two-piece wheels (disc portion 1B) includes two major parts, an outer portion (or rim half) 3 and an inner portion (or rim halt) 4. The two portions/halves 3 and 4 are held together by fastening elements such as assembly studs 5 which extend through overlapping portions of the two rim halves 3 and 4 and assembly nuts 6 and sealed with a wheel sealing o-ring 7 placed between confronting surfaces of the two portions 3 and 4 so as to prevent air from escaping out of tire air chamber 2B (thereby creating a sealed space including tire cavity/chamber 2B). An inflation valve 8 is in communication with cavity 2B via an internal passageway 9, allowing controlled ingress and egress of air (or other fluids) for inflation/deflation purposes.
With this type of construction, if some of the fastening elements such as assembly nuts 6 are disassembled from studs 5, pressure is sometimes relieved in a manner that avoids the previously described consequences. This is due to the fact that loosening of some of the assembly nuts 6 may allow the outer portion 3 of the wheel assembly 1 to deflect enough that the o-ring 7 seal can leak and relieve pressure. However, as wheels become stronger and stiffer to carry higher loads or higher inflation pressures, the wheel halves 3, 4 also become stronger and stiffer. In this case, removing some of the assembly nuts 6 may not allow the wheel components to deflect sufficiently to release trapped air and alleviate the air pressure issue. (This is a particular problem on very large wheels and tires used for industrial applications, such as tires used on earth moving equipment, but it can also be a problem in smaller wheels and tires). In this case, after a number of the assembly nuts 6 are removed, the remaining studs 5 and nuts 6 holding the wheel assembly 1 together may fail catastrophically injuring the personnel disassembling the unit.
FIG. 2 shows a two piece wheel assembly 10 and tire with a central tire inflation (CTI) valve 11. The construction of wheel 10 is the same as the one shown in FIG. 1, except it has the CTI valve 11 added. The CTI valve 11 is a device used to control the pressure in tire cavity 2B according to a controlled setting from the cab of the vehicle via internal passageways 12, 13. However, these systems only cover specific pressures and the valve 11 does not totally relieve the pressure in the tire cavity 2B, and cannot serve as a safeguard in the situations outlined herein. Other means have also been sought to relieve the pressure in the tire such as that described in U.S. Pat. No. 5,343,920. This system describes special assembly studs and nuts that are designed to relieve the pressure in the tire if any of the assembly nuts are removed from the vehicle. However, this system also has numerous disadvantages. First, the assembly is complex, requiring a multiplicity of components that can fail. Second, studs are weakened by the o-ring sealing device of the aforesaid system. Third, the assembly nuts may have to be oversized in order to seal air pressure in the system. Fourth, multiple assembly studs must have the sealing device and corresponding cross-drills into the tire cavity. Fifth, there are multiple leak points which reduce the liability of the system. Sixth, the design of the studs and nuts is complex, adding to the cost of this system.
The instant invention resolves and avoids these difficulties by teaching designs for automatically relieving/releasing pressure from a sealed tubeless wheel/tire assembly as part of its disassembly. Thus, in the instant invention, wheels having fastening elements comprising mechanical holding apparatus such as nuts and bolts (or studs) used to hold together two parts to seal the vessel comprised of the rim and a tubeless tire mounted thereon are provided with a blocking device that prevents loosening and/or removal of said nuts, bolts and/or other mechanical holding apparatus serving as fastening element(s) until said blocking device is first removed from its blocking position. Removal directly or indirectly causes or requires the opening of a pressure relief channel or channels, which is/are advantageously formed by an air passageway in the rim, allowing, enabling and/or effecting depressurization of the sealed pressure vessel. The foregoing features and others of the inventive concept, as more fully described below, provide numerous advantages over the systems of prior art. To begin with, the described inventive concept and its variations is/are (in contrast to prior art) durable, reliable, relatively simple in construction and operation, and virtually fool-proof in terms of avoiding and preventing the types of explosive and catastrophic failures described above. The numerous other advantages of our invention will become more apparent in view of the more detailed description and claims that follow.